The ‘fizzing sensation’ of sherbet is formed by an acid-base chemical reaction between citric acid and baking soda (which is a base), in the presence of a liquid (which in this case, is your saliva), causing tiny bubbles of carbon dioxide (CO2) that tickle your tongue.

Fizzing Lemonade
Lemons, sugar, baking soda, water, bowl/jar for mixing, measuring spoons, spoon for mixing
Squeeze (and strain) the juice of one lemon into a glass
Add 1 teaspoon of bicarbonate of soda (we added it by the 1/2 teaspoon to see multiple reactions)
Give it a stir to really get the reaction happening!
Add some sugar to water to taste and add to lemon mixture. (There should be more frothing but not as big as the first reaction. Why do you think that is?)
Taste your lemonade! (What can you notice? What can you feel on your tongue?)

What's happening?
When the lemon juice (acid) and the bicarbonate of soda (base) mix, they form a chemical reaction known as an acid-base reaction. This is the same sort of reaction that you get when you mix bicarb soda and vinegar, such as in the classic erupting volcano experiment. The reaction produces as gas called carbon dioxide (CO2) which creates bubbles when formed in a liquid like in this fizzing lemonade experiment. This process is called carbonation.
Handy Tips:
- Play around with the quantities. Add more lemon for a greater citrus taste, add more bicarb of soda for greater fizz, add more water to dilute, add more sugar to make it sweeter. What is your perfect combination?